In an automotive emission control system, a pump supplies air as required to the exhaust system between the manifold and the catalytic converter. In conventional regenerative pumps intended for use in an automotive emission control system, the impeller has straight radially extending blades at its outer periphery and is driven in rotation between a pump housing and a cover formed with a pump chamber. The pump chamber is formed symmetrical with respect to the rotatable impeller, and the surfaces of the housing and the cover. Further descriptions of toric pumps of this construction can be obtained from U.S. Pat. Nos. 5,302,081; 5,205,707 and 5,163,810.
Over time, industry needs have changed as restrictions on emissions have changed. It is now desirable to provide more air to an automotive emission control system than was previously required. Currently, it is desirable to provide at least between 19 and 20 cubic feet per minute (cfm). It is also desirable to meet the minimum fluid flow requirements while maintaining the same size housing. To meet these new fluid flow requirements, it has been necessary to double, and in some instances quadruple, the currently existing fluid flow rates of regenerative single stage pumps. Up to this point in time, the typical regenerative pump used in automotive emission control system applications has been capable of achieving a fluid flow rate of only 4 cubic feet per minute (cfm) at approximately 40 inches (H.sub.2 O) head, and therefore, it is desirable in the present invention to provide a greater fluid flow output at the same or greater pressure for a given size housing configuration. It is further desirable in the present invention to reduce the electrical current or power requirements for a motor used in an electric motor driven pump for a given pressure and/or flow output. It is also desirable in the present invention to reduce the rotational speed of the motor required for a given pressure and/or flow rate output. Additionally, it is desirable in the present invention to increase overall efficiency and to provide for longer life and enhance reliability of regenerative pumps, and in particular, single stage, double channel, electrical air pumps or compressors.